Preparation

Make crust:
Mix flour, sugar, cinnamon, nutmeg and salt in processor. Add butter. Using on/off turns, process until mixture resembles coarse meal. Mix in vanilla and enough ice water by tablespoonfuls to form moist clumps. Gather dough into ball; flatten into disk. Wrap in plastic and refrigerate until firm, about 2 hours.

Bake crust until set but still pale in color, piercing with fork if crust bubbles, about 20 minutes. Transfer to rack; cool. Increase oven temperature to 400°F.

Make filling:
Combine sugar and 1/4 cup water in heavy medium saucepan. Stir over medium-low heat until sugar dissolves. Increase heat. Boil without stirring until caramel is deep amber color, occasionally brushing down sides of pan with wet pastry brush and swirling pan, about 9 minutes. Reduce heat to medium. Gradually whisk in cream (mixture will bubble). Stir until caramel is smooth. Add butter, honey and vanilla. Stir until well blended. Mix in all nuts.

Stir white chocolate in top of double boiler set over hot water just until melted and smooth. Remove from over water. Using fork, drizzle chocolate decoratively over tart. Let stand until chocolate is set, about 30 minutes. (Can be made 8 hours ahead. Let stand at room temperature.)